cells of the conjunctiva and cornea that together with lacrimal gland comprise much of the lacrimal functional unit (LFU). Viewed collectively, the LFU is the primary source of lacritin in the body, and the eye the main target. Disease Dry eye is the most common eye disease, affecting 5 - 6% of the population. Prevalence rises to 6 - 9.8% in postmenopausal women, and as high as 34% in the elderly. Tears lubricate the lid and are important for the refraction of light. Tears also promote epithelial health. Only a small fraction of the estimated 1543 proteins in tears are differentially deficient or upregulated in dry eye. Lacritin monomer is differentially downregulated in mild to severe aqueous deficient dry eye, and in contact lens-related dry eye. In a larger trial, 95% of tears from patients with aqueous deficient dry eye were lacritin monomer deficient. Two studies that did not differentiate monomer from multimer did note any change of lacritin in dry eye. Topical treatment of eyes of dry eye mice (Aire knockout mouse model of dry eye) restored tearing, and suppressed both corneal staining and the size of inflammatory foci in lacrimal glands. Lacritin monomer deficiency in tears of patients with blepharitis was also reported. Blepharitis is an inflammation of the eyelid often associated with dry eye. In climatic droplet keratopathy, N119 appears to be un-glycosylated. Also a normal breast cancer localization reported by some has not been replicated in Unigene (the 'mammary gland' hit is for breast cancer) and gene array studies, but some breast cancers appear to display elevated expression or LACRT gene amplification. iTRAQ analysis of tears from diabetics at different stages of disease detected relatively more lacritin, lysozyme, lipophilin A, lipocalin 1, immunoglobulin lambda chain and lactotransferrin in tears of patients with diabetic retinopathy. The analysis did not distinguish lacritin monomer from polymer, and proposed the application of all as biomarkers. Tear lacritin monomer is barely detectable in the initial stage of infection by Fusarium solani in fungal keratitis. Also down regulated are tear lipocalin-1 and cystatin S. Fungal keratitis accounts for half of all corneal ulcers in Africa and India - the primary source of blindness in these countries. Phase II clinical trial of 'Lacripep™ in Subjects With Dry Eye Associated With Primary Sjögren's Syndrome' (NCT03226444) is complete. Lacripep™ is lacritin synthetic peptide 'N-94/C-6'. References Further reading External links Glycoproteins